Embodiments of the invention relate to an auxiliary turbomachinery shaft support system that may be applied to a centrifugal compressor. In particular, it relates to a shaft support system for turbomachinery of the type comprising magnetic bearings, which may be of the active type.
As known, turbomachinery may have a shaft, on which a plurality of devices may be mounted, for example turbines, centrifugal impellers, axial impellers etc. The shaft and the devices form a rotor assembly that is rotationally supported by bearings, which may be magnetic bearings.
As long as the magnetic bearings are operating correctly, they levitate the rotor and maintain the shaft in position by applying controlled electromagnetic forces on the rotor in radial and axial directions.
As known, magnetic bearings may be affected by malfunctioning, power loss or by temporary overloads that may lead to the loss of the shaft levitation.
To prevent an unwanted movement of the shaft and therefore damages deriving to those incidental circumstances, the shaft may have auxiliary support systems, also called landing systems, which may prevent damages to the turbomachinery.
Conventionally, this function of landing is provided by auxiliary angular contact ball bearings mounted on the shaft and designed to contain both the radial and axial forces induced by the incidental event.
The maximum number of landings that the angular contact ball bearings may support is mainly linked to the maximum axial force acting on the bearings.
In large turbomachinery, axial forces acting on the angular contact ball bearings are considerable and therefore their operating life is severely limited.